This invention relates to the art of thermostats and, more particularly, to a thermostat system having a xe2x80x9cvacationxe2x80x9d mode of operation in which the environment of a space supervised by the thermostat system is maintained at energy-saving levels while the space is unoccupied. More particularly, this invention relates to such a thermostat system which, when operating in xe2x80x9cvacationxe2x80x9d mode, issues commands to various devices situated in and around the conditioned space to provide an appearance of ongoing occupancy.
Thermostats have been used for many years as temperature sensitive devices which controls heating and/or cooling equipment for conditioning a space in which the thermostat, or a temperature sensor connected to a thermostat, is placed. In the well known manner, a simple thermostat can be adjusted to establish a temperature set point such that, when the temperature in the conditioned space reaches the set point, the thermostat interacts with the heating and/or/cooling equipment to take suitable action to heat or cool the conditioned space as may be appropriate for the season and conditions.
Modern thermostat systems, which take advantage of the ongoing rapid advances in electronic technology and circuit integration, have many features which provide more precise supervision of the heating and/or cooling equipment to achieve more economical and more comfortable management of the temperature of a conditioned space. Many modern thermostat systems include a real time clock, a memory and a data processor to run a process control program stored in the memory to accurately measure the temperature of a temperature sensor disposed in the conditioned space and to send control signals to the heating and/or cooling equipment to closely control the temperature of the conditioned space. Modem thermostat systems permit anticipating and minimizing hysterisis or overshoot of the temperature in the conditioned space. In addition, the program can specify different set points at different times of the day and week and may also include a xe2x80x9cvacationxe2x80x9d mode which employs different set points when the conditioned space is not occupied for an extended period.
Many modern thermostat systems are programmable by a user by selectively placing the process control program into a programming mode. Typically, prior art programmable thermostat system employ a tactile touch pad with various fixed position buttons to be touched in a precise sequence to program set points (which may vary with the day of the week) for programmable time periods which may include a xe2x80x9cvacation modexe2x80x9d. The programming sequence may be followed on a separate display, typically a liquid crystal display.
When a thermostat system is placed into the xe2x80x9cvacation modexe2x80x9d in contemplation of the conditioned space being unoccupied for a period, there may be a concurrent desire, for security reasons, to establish a pattern for actuating and deactuating various electrical devices in and around the conditioned space to provide an indication that the space remains occupied. The present thermostat system integrates these tasks in a highly convenient, efficient and effective manner.
Briefly, a thermostat system for controlling space conditioning equipment includes a temperature sensor for providing an electrical signal indicative of the temperature of a conditioned space and a processor having a central processing unit, a memory for storing program and data information and an input/output unit. The input/output unit has a sensor input coupled to the temperature sensor, a control output sending control signals to the space conditioning equipment and also an electrical device interface adapted to establish communications between the processor and a plurality of addressable electrical devices situated within and proximate the conditioned space. In operation, when the system is in a vacation mode the processor issues a pattern of actuate and deactuate commands to the addressable electrical devices to provide the illusion of ongoing occupancy. In one preferred embodiment, communications between the processor and the electrical devices takes place over the local line power system, for example, in accordance with the X10 protocol. In another preferred embodiment, the processor sends commands via infrared to an electrical device controller which resends the commands over the local line power system to the electrical devices.